Sydney broadcaster Alan Jones has defied a growing social media campaign and his political enemies to return to the airwaves this morning.

A total of 15 companies have pulled support from his show in the wake of his controversial comments that Julia Gillard's father died of shame because of what Mr Jones said were her lies.

Opening his breakfast program this morning, Jones told listeners he was wrong to make the comments.

"Those listening to this program know that when I'm wrong, I have no difficulty in admitting I'm wrong," he said.

"So I say on this program upfront, my apology to Julia Gillard, which I sought to deliver to her in person but she chose not to take my call, which is her entitlement, my apology is without qualification or reservation.

"When I opened the press conference to the media, a range of questions were asked of me which bore on public policy and the performance of the Gillard Government and my attitude to all of that.

"Those answers should not be interpreted as representing a qualification of what I said then and what I say now. The comments were wrong, they were over the top."

On Sunday, Jones publicly apologised for his comments made at a Young Liberals dinner a week earlier.

Those people who have complained about what I said about the Prime Minister and the language I used are using vile language in their comments about me.

Alan Jones

Yesterday several advertisers of Jones's radio program including Freedom Furniture, Mercedes-Benz and Coles pulled their support in the face of a mounting online campaign urging advertisers to boycott his program and radio station 2GB.

He says the backlash is an attempt to silence him.

"Well, I've got news for these people: I don't back off and I don't frighten easily," he said.

"And those people who have complained about what I said about the Prime Minister and the language I used are using vile language in their comments about me.

"That apparently is OK. I don't mind, I can cop it and I can wear it and I'm not complaining, but if the criticism and the pressure and the headlines and the stories and the intimidation are designed to silence me in what I do on this program, then I'm sorry.

"The bad news is you've picked the wrong bloke."

Listeners of 2GB have called in to offer Jones their support:

You have my support, buddy. I tell ya right now, you stay there, and they can shove it in my book.

Listen ol' mate, I reckon you said the wrong thing but I support you and I think you ought to keep rolling on.

Good morning Alan. I believe you were wrong in what you said, but I am so proud to have a man stand up and apologise.

Alan, you are a champion and you do a lot for people. These people are just attacking you because they are jealous, mate.

Veteran Liberal MP Bronwyn Bishop also called in to offer her support to Jones, as did billionaire businessman Kerry Stokes.

An online petition calling for Jones to be taken off air has been signed by more than 78,000 people.

Political fallout

Labor MPs are trying to link the comments of Jones, a fervent critic of the Government, to the Liberal Party and Opposition Leader Tony Abbott.

Former prime minister Kevin Rudd has defended Ms Gillard and attacked the broadcaster.

"What this guy suffers from is from absolute delusions of grandeur, and I think that's been cultivated by his intimate association with previous conservative leaders over a long period of time," Mr Rudd said.

"I think this is where Mr Abbott has a responsibility of leadership. We all know he's a personal friend of Mr Jones, but really he should A, kick him out of the Liberal Party; B, ban him from future Liberal Party functions; and C, never appear on his program again."

Talk about going over the top. I'm surprised they're not calling for him to be hanged the way they're going on.

Alexander Downer

But former Howard government minister Alexander Downer says Labor is using one gaffe to wage a "disgraceful" anti-Liberal campaign.

"Paul Keating described the Liberals as dogs going back to eat their own vomit, and my father was attacked - a man who spent three-and-a-half years in a Changi prisoner of war camp - by the Labor Party as being a coward," Mr Downer said.

He says the comments Jones made have been blown out of proportion.

"Alan Jones has made an inappropriate comment about the Prime Minister's father and nobody would debate that and he's apologised for it.

"But talk about going over the top. I'm surprised they're not calling for him to be hanged the way they're going on.

"I mean grow up, get over it and move on."

'Thuggery'

Meanwhile, the author of the Government's climate change review, Ross Garnaut, has described Jones as a "thug" and a "headkicker".

Jones has previously described climate science as witchcraft and called Professor Garnaut an idiot.

Speaking to the ABC's Lateline, Professor Garnaut said Jones was a manifestation of the serious degeneration of Australian media and political culture.

"The degeneration's associated with the crowding out of information and analysis by noise, by abuse, by thuggery," he said.

"If we don't correct this degeneration of our political culture, Australia's got no hope of dealing with the serious problems in the period ahead.

"It's much more difficult in the last few years to seriously analyse a serious issue like the ones we are talking about ... without the thugs and headkickers ... Alan Jones and their ilk."